Book/Report

FZJ-2019-05082

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Kinetik der Methan-Dampf-Reformierung

Drescher, I. (Corresponding author)FZJ*

1999
Forschungszentrum Jülich, Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/23105

Report No.: Juel-3699

Abstract: The methane steam reforming is a possibility to use natural gas for the fuel cell technology. The anode of the high temperature fuel cell SOFC$^{1}$ consists of a Nickel cermet (Ni/YSZ$^{2}$) which serves to catalyze the steam reforming reaction directly at the SOFC anode. This internal reforming is an interesting option for cost reduction and higher efficiency of the SOFC system. The quite endothermic and fast reforming reaction leads to proclems in the heat balance of the fuel cell. To get the heat balanced, a thorough knowledge of the reforming kinetics on SOFC-anodes at operating conditions is required. In this work the kinetics of the steam reforming reaction of CH$_{4}$ are studied at temperatures of 600$^\circ$C - 700$^\circ$C and partial pressures of 3.9 $\le$ p$_{ch_4}$ $\le$ 20.3 kPa and 0 $\le$ p$_{H_{2}O}$ $\le$ 31.2 kPa st ambient pressure (p = 101.3 kPa) on a NI/YSZ catalyst. The SOFC anode is crashed to small particles of diameters of 125 $\mu$m $\le$ d$_{cat}$ $\le$ 250 $\mu$m. The choice of this particle size, in the order of the determined reaction depth, avoids rate limitaions by intraparticle mass transfer. The active nickel surface is determined by CO and hydrogen adsorption measurements, that rnders feasible a normalization of the measured reforming rate on the nickel surface. A rate expression with competitive Langmuir-Hinshelwood adsorption of methane and water vapor is well describing the experimental data. Adsorption measurements in a temperature region of 600$^\circ$C - 800$^\circ$C are worked aut to estimate the advantage of the decrease in working temperature of the SOFC to 650$^\circ$C for the internal methane steam reforming. The reaction of adsorbed methane with isotopic marked steam (D$_{2}$O) in the gas phase as well as the reaction of adsorbed D$_{2}$O with methane in the gas phase are used to determine the methane and the steam adsorption on NI/YSZ. The investigation of the reaction of D$_{2}$O with the adsorbed species of the methane steam reforming serves for the determination of the rate determined step.

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000 ; Retrocat)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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